linkbacks: fix tab visibility if excluded

* Adds module to excluded packages and disables tab in detailed record
  view.  (closes #1707)

* NOTE Adds deprecation warning for linkbacks module.

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
I thought of a "multi-level defence", i.e. disable it everywhere in sight, even up to requiring multiple unlocks to use.  But I guess this is OK too.